Effect of higenamine on action potential of Purkinje's cells and ventricular myocardial cells in dogs
Yu, G.R.; Qiao, S.Y.; Zheng, D.S.; Huang, M.X.; Bian, Y.T.
Journal of Traditional Chinese Medicine 4(2): 133-140
1984
ISSN/ISBN: 0255-2922 PMID: 6567726 Document Number: 237713
Action potentials of isolated Purkinje's cells in dogs and the electrophysiological actions of dl-demethylcoclaurine (DMC) on dog Purkinje's cells were studied by glass microelectrodes. The effects of DMC on the action potential of Purkinje's cells were: (1) increase of amplitude of the plateau phase; (2) enhancement of repolarization of phase 3 and shortening of APD; (3) DMC (1 .times. 10-7 g/ml) caused a shortening APD without any significant change of the ERP, while DMC (1 .times. 10-6 g/ml) caused shortening of both APD and ERP; (4) DMC (10-6 g/ml) increased the slope of phase 4, decreased the threshold of depolarization, and increased the automaticity of the Purkinje's cells; (5) the action of DMC on the Purkinje's cells was only partially blocked by tetraodontoxin and verapamil. The above results suggest that: (1) LMC enhances the influx of both Na+ and Ca++ in slow channel; (2) relatively high concentrations of DMC may induce tachyarrhythmias, while lower concentrations may prevent the arrhythmias; (3) DMC may increase the ventricular rate in patients with complete heart block above bundle of His but not in blockages below His bundle; (4) there is a slight increase of ERF by low concentration of DMC. DMC thus appears safer than isoproterenol in the treatment of bradyarrhythmias.